Three rather cosmetic suggestions ...

[Jörn Reppenhagen]

No big deals.

1. Missing blanks, like in "23.97MP", "XF18-55mmF2.8-4 R LM OIS".
   Using blanks at the correct places just makes reading and recognizing the data at first glance easier: "23.97 MP", "XF 18 – 55 mm, F 2.8 – 4, R LM OIS". – Looks far better, hmm?
   It's a common problem, seen almost everywhere. Stil nice if done right.
    
2. No focus change if moving the mouse pointer to a different area after using a slider.
   Example: Changing the opacity of a layer or size of a brush. When done, I need to click somewhere outside the slider panel for closing it.
   Causes two problems:
   After changing opacity, I always find myself clicking the next UI control for using it, but it doesn't react. Because the first click after setting opacity is needed for closing the slider.
   After changing the brush size, I need to see the new size. But Affinity doesn't show the new size until I close the slider by clicking somewhere. Of course I click into the picture. Causing the slider to close - but at the same time activating the brush function: Voilá - selection changed, or a big fat blob of color in the picture, which I don't want.
   Would be nice if the sliders close as soon as I move the mouse pointer away.
   That way, I'd be able to click the next UI element without doing that slider-close-click, and without applying the newly sized brush at places where I don't wish to apply it.
    
3. Size of the (how it's called?) "slider knobs" .
   I am aware of the fact that tiny "knobs" look nice and highly precise. And I am quite at home with using a mouse.
   But an option for changing the "knobs" size would still be great.
   We usually concentrate on that "knob's" effects on the picture. Thus we click that "knob", but at the same time our eyes swing back to the picture for watching the effect. And in quite some cases, there's no effect because we missed the tiny "knob".
   Maybe it's just me?

As said: No big deals, just cosmetic improvements.
 

[Fixx]

2 hours ago, Jörn Reppenhagen said:

Size of the (how it's called?) "slider knobs" .

There is no need to change the visual size, but the actual active effect area could be bigger. That is, knob should move even if mouse drag is a few pixels off.

[Jörn Reppenhagen]

Fixx: Of course, that's the technique behind it, changing the container size.
But adapting the visual size would still be a sound idea - the human brain is a quite strange thing.
Even if we knew there's some tolerance around the visual "knob", we'd still try to hit it straight in the middle; thus not much gained as it would take a quite similar degree of concentration.

I guess developers chose that tiny sizes for two reasons: Looks highly professional - and gives enough room for clicking left and right of the "knob" (someone please tell me the correct technical term ) for being able to select an absolute value with a single click - without creating a large deadzone around the "knob".

Regarding the professional look, there's always a chance of overdoing it - just take that tiny LR triangles as an example. At least for me, it's a kind of hindrance, as I wish to concentrate on the picture, not on sharpshooting the UI elements.
As for that left and right clicks: I always find myself choosing relative values by moving the sliders, just rarely clicking left or right. But that's just my personal habit.
That's why it might be a nice idea being able to select the "knob" size - all according to working habits. - But of course I am aware of the programming effort behind such "simple" requests.

Reminds me of my days as a programmer ...
Customer: "Hey Jörn, there's just this itsy-bitsy tiny little mini change we like you to do on the UI - matter of seconds!"
Me: "There goes my weekend ..."